In processes involving printing on sheets of material such as paper, or processing folding carton blanks, it is typically desirable that in the case of a rectangular sheet or blank that the side edges of the sheet or blank are parallel to the conveying direction and/or the leading edge is perpendicular to the conveying direction. This allows operations such as printing to be properly oriented with respect to the sheet or blank. In carton folding/gluing operations, flat carton blanks are folded along score lines and glued along a seam or at a corner or corners to provide a carton ready for subsequent uses such as erecting or filling. Carton folder/gluers typically include a feeder which dispenses a flat, die-cut carton blank from the bottom of a stack of blanks. These feeders often do not dispense a carton blank with the desired orientation alignment because of many factors, e.g., asymmetry of carton shape and uneven weight distribution in the feeder, varying feeder belt friction coefficients, differences in feed gate settings and other factors. Immediately after leaving the feeder, cartons are gripped by carrier belts. To create a desired spacing between each carton blank on the carrier belts, the carrier belts run faster than the feeder belts. This creates a brief ‘tug of war’ while the carton is released by the slower moving feeder belts and engaged by the faster moving carrier belts. The feeder and carrier belt positioning is often asymmetric with respect to the carton and this ‘tug of war’ can cause a carton blank to twist out of the desired orientation.
Folder/gluer operators strive to make cartons feed “square” or “aligned”, i.e., in the desired orientation with the conveying direction on carrier belts. This requires a high degree of operator skill based on years of experience.
To reduce the level of operator skill required to some extent and to better assure proper orientation regardless of machine parameters that often vary during operation, carton folders/gluers often include a carton aligner or aligning section. In prior art aligning processes, the sheets or carton blanks have been conveyed by carrier belts with overlying balls or rollers that lightly grip the sheet or blank and laterally urge the sheet or blank against a mechanical guide comprised of an adjustable steel plate with a smooth, flat surface. This section of the machinery is known as an aligning section. The loose contact between belts and rollers allows the sheet to shift so that it can become aligned with respect to the guide which typically sets one side edge of a blank parallel with subsequent lower carrier belts and upper gripping belts or rollers. This is intended to desirably align the sheet or blank for subsequent operations.
There are some drawbacks to the prior art method of aligning:                Set up of the aligning section involves adjusting numerous components and variables and requires an experienced operator.        The sheet or blank is not firmly gripped or controlled during the aligning process. Thus the speed and position of the blank in the aligning section is not well defined, repeatable, or predictable. There are some subsequent processes such as applying adhesive with systems provided by Nordson of Westlake, Ohio or applying window film patches with windowing systems such as provided by Tamarack Products of Wauconda, Ill. that require the speed and position of the blank to be known so that subsequent speed and position can be accurately predicted. For example, the Tamarack® Vista® windowing machine uses a scanner approximately two feet ahead of the Vista windower to sense carton position. Carton speed is indirectly sensed by an encoder that measures the speed of a lower carrier belt. During aligning, substantial slippage occurs between the blank and the carrier belts in the aligning section, the carton speed will not be sensed properly, the blank's subsequent position will not be predicted accurately, with the result that the window application position will not be accurate. For these applications, the carton blank must be sensed later in the process, after aligning. This means the scanning of the blank must occur later in the folder/gluer and this can result in an undesirable or impractical location for the Vista windower.        